Motor driven cabin air compressor with variable diffuser

ABSTRACT

An air cycle machine is provided and includes a compressor section having a variable area diffuser, a turbine section having an inlet nozzle with a variable size, a motor to drive the compressor and a common rotating shaft on which the compressor section, the turbine section and the motor are mounted, the turbine section driving rotation of the shaft to drive the compressor section with the motor.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a motor driven cabin aircompressor with a variable diffuser.

Aircraft environmental control systems incorporate turbomachines,commonly referred to as air cycle machines (ACMs), to help facilitatecooling and dehumidifying air for supply to a cabin of an aircraft. Aircycle machines can include two or more wheels having at least onecompressor and at least one turbine disposed axially along the sameshaft. On aircraft powered by gas turbine engines, the air to beconditioned in the air cycle machine is generally either compressed airbled from one or more of the compressor stages of the gas turbine engineor air diverted from another location on the aircraft. With eithersystem, the air is passed through the compressor(s) of the air cyclemachine where it is further compressed and then passed through a heatexchanger to cool the compressed air sufficiently to condense moisturetherefrom. The dehumidified air continues through the environmentalcontrol system back to the turbine(s) of the air cycle machine. In theturbine(s), the air is expanded to both extract energy from thecompressed air so as to drive the shaft and the compressor(s) coupledthereto and cool the air for use in the cabin as conditioned coolingair.

To meet required specifications for providing fresh air and maintainpressurization to the cabin during flight, environmental control systemson larger aircraft employ two separate (dual) air conditioning packs.Unfortunately, operating dual air conditioning packs may not benecessary or efficient in some circumstances such as when the plane ison the tarmac. In this instance and others, operating only a single airconditioning pack could accomplish the conditioning of air for thecabin.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, an air cycle machine isprovided and includes a compressor section having a variable areadiffuser, a turbine section having an inlet nozzle with a variable size,a motor to drive the compressor and a common rotating shaft on which thecompressor section, the turbine section and the motor are mounted, theturbine section driving rotation of the shaft to drive the compressorsection with the motor.

According to another aspect of the invention, an air cycle machine isprovided and includes a compressor section having a variable areadiffuser to compress inlet air, a turbine section having an inlet nozzlewith a variable size to receive the compressed air from the compressorsection and to expand the air for use in an aircraft cabin, a motor todrive the compressor and a common rotating shaft on which the compressorsection, the turbine section and the motor are operably mounted, theturbine section driving rotation of the shaft to provide additionaldrive power to the compressor section along with that of the motor.

According to yet another aspect of the invention, an air cycle machinefor use in a RAM engine in an aircraft is provided and includes acompressor section having a variable area diffuser to compress RAM inletair, a turbine section having an inlet nozzle with a variable size toreceive the compressed air from the compressor section and to expand theair for use in a cabin of the aircraft, a motor to drive the compressorand a common rotating shaft on which the compressor section, the turbinesection and the motor are operably mounted, the turbine section drivingrotation of the shaft to provide additional drive power to thecompressor section along with that of the motor.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of an air cycle machine for an environmentalcontrol system of an aircraft;

FIG. 2A is an enlarged view of a turbine inlet nozzle of the air cyclemachine with a poppet member in a first position;

FIG. 2B is an enlarged view of the turbine inlet nozzle of the air cyclemachine with the poppet member in a second position;

FIG. 3 is a partially broken view of a variable area diffuser in thedirection of arrows 2-2 of FIG. 4;

FIG. 4 is an enlarged cross-sectional view of a variable area diffuser;and

FIG. 5 is a schematic illustration of the air cycle machine.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic view of an environmental control system (ECS)10. The environmental control system 10 includes an air cycle machine 12that receives air 14 that is conditioned by various devices symbolicallyindicated as 16A, 16B, and 16C to produce air flow at a desiredtemperature and pressure for aircraft cabin C. The air cycle machine 12includes a compressor section 18, a shaft 20, and a turbine section 22.The compressor section 18 has a compressor inlet 24, a compressor wheel26 and a compressor outlet 28. The turbine section 22 includes a turbineinlet 30, turbine inlet nozzle 32, turbine wheel 34 and turbine outlet36.

System air 14 is bled from one or more of the compressor stages of thegas turbine engines of the aircraft or directed from an air source atanother location on the aircraft. One or more devices 16A can condition(e.g., preheat, acoustically treat) the air 14 prior to its entry intothe air cycle machine 12. The air 14 enters the air cycle machine 12 atthe compressor section 18 through the compressor inlet 24. The air 14 iscompressed to a higher pressure by the compressor wheel 26, which ismounted on the shaft 20 for rotation about axis A. The compressed air 14is output to the remainder of the environmental control system 10 viathe compressor outlet 28. Air 14 output from the compressor section 18is conditioned by various devices 16B to change the characteristics ofthe air 14 that enters the turbine section 22 via the turbine inlet 30.These devices 16B can include heat exchangers, condensers, and/or waterextractors/collectors that condition the air 14 to a desired pressureand temperature.

The turbine inlet nozzle 32 receives air 14 entering the air cyclemachine 12 through the inlet 30 and is disposed adjacent the turbinewheel 34 to direct the flow of air 14 thereto. As will be discussedsubsequently, the air cycle machine 12 is configured with a valve tovary the size of turbine inlet nozzle 32 as desired to better optimizethe efficiency of the environmental control system 10. In particular,the selectively variable turbine inlet nozzle 32 disclosed herein allowsthe power consumption of the environmental control system 10 to bereduced, for example, by operating only a single air conditioning packto condition the cabin rather than operating two air conditioning packsin some instances.

The turbine wheel 34 is mounted on the shaft 20 to drive rotation of theshaft 20 and compressor wheel 26 about axis A. After passing through theturbine inlet nozzle 32 the air 14 is expanded to both extract energyfrom the air 14 so as to drive the shaft 20 and the compressor wheel 26(in combination with a motor 38 mounted along the shaft 20 in someembodiments) and to cool the air 14 to prepare it for the cabin. Afterexpansion, the air 14 passes through the turbine outlet 36 out of theair cycle machine 12. The air 14 can pass through one or more devices16C (e.g., heat exchangers, compact mixers, and/or acoustic treatmentdevices) before reaching the cabin C at the desired temperature andpressure.

FIG. 2A is an enlarged view of the turbine section 22 with a poppetmember 40 disposed in a first position extending into the turbine inletnozzle 32. In addition to the turbine inlet 30, the turbine inlet nozzle32, the turbine wheel 34, the turbine outlet 36, and the poppet member40, the turbine section 22 includes a shroud 42, a first cavity 44, avalve body 46, and a second cavity 48. The shroud 42 has a passage 50.The poppet member 40 includes a main body 52 and seals 41A and 41B. Anarcuate plate 54 is fixed within the turbine inlet nozzle 32.

As illustrated in FIG. 2A, the poppet member 40 is slidably mounted onthe stator shroud 42 and is configured to seal the first cavity 44 fromthe turbine inlet nozzle 32. In particular, seals 41A and 41B aredisposed between the poppet member 40 and the shroud 42 to allow forpressurization of the first cavity 44. The first cavity 44 serves as anannular plenum that is defined by portions of the shroud 42, the poppetmember 40, the valve body 46, and other portions of the casing of theair cycle machine 12. The valve body 46 is mounted in fluidcommunication with the first cavity 44.

The valve body 46 can be any valve commonly known in the art forselectively communicating air from two ports (two pressure sources) to athird port. The valve body 46 can be controlled to move a member betweena first position that blocks a first of the three ports and allows thesecond and third ports to be in fluid communication, and a secondposition that blocks the second port and allows the first and thirdports to be in fluid communication. The valve body 46 is controlled tovary the pressure in the first cavity 44 between a first pressure P₁,equal to or about equal to the pressure P_(t) within the turbine inlet30 (illustrated in FIG. 2A), and a second lower pressure P₂, equal to orabout equal to an ambient pressure P_(a) external to the environmentalcontrol system 10 and air cycle machine 12 (illustrated in FIG. 2B).Thus, the valve body 46 is selectively controlled to allow for fluidcommunication between the first cavity 44 and either the turbine inlet30 or the ambient air source external to the air cycle machine 12. Inthe first position shown in FIG. 2A, the first cavity 44 is in fluidcommunication with the turbine inlet 30. The higher first pressure P₁that results from this arrangement forces the poppet member 40 outwardexpanding the volume of the first cavity 44. Thus, in the firstposition, the poppet member 40 extends from the first cavity 44 into theturbine inlet nozzle 32 to reduce the size (volume and/orcross-sectional area) of the inlet turbine nozzle 32 that receives air14 from the turbine inlet 30. In this position, the poppet member 40restricts the flow of air 14 to the turbine wheel 34. The reduced airflow to the turbine wheel 34 maybe desirable in some instances, forexample, if it is necessary to operate both air conditioning packs tomaintain the cabin at a desired pressure and temperature.

The second cavity 48 is defined by the shroud 42 and the poppet member40 and is positioned radially outward of the turbine wheel 34 withrespect to axis A. The poppet member 40 separates the first cavity 44from the second cavity 48. The passage 50 through shroud 42 allows thesecond cavity 48 to be in fluid communication with the turbine inletnozzle 32 immediately adjacent to the turbine wheel 34. This arrangementallows the second cavity 48 to be maintained at or about the staticpressure experienced within the turbine inlet nozzle 32 immediatelyadjacent to the turbine wheel 34. This static pressure is lower than thepressure at the turbine inlet 30 (and selectively the pressure of thefirst cavity 44) but greater than the ambient pressure external to theair cycle machine 12 (and selectively the pressure of the first cavity44), which allows for actuation of the poppet valve 40.

The poppet valve 40 includes a main body 52 that is mounted on theshroud 42 and configured to seal and separate the first cavity 44 fromthe second cavity 48. The main body 52 is actuated as discussed to sliderelative to shroud 42. In the first position shown in FIG. 2A, the mainbody 52 extends from the first cavity 44 and shroud 42 into the turbineinlet nozzle 32. The arcuate plate 54 is fixed to the turbine inletnozzle 32 and divides the turbine inlet nozzle into two sections. Theplate 54 is aligned within the turbine inlet nozzle 32 so as tominimally interfere with the direction of airflow toward the turbinewheel 34. In particular, the plate 54 is configured with a smallcross-sectional area interfacing the airflow and has a larger surfacethat extends generally parallel to one of the walls of the turbine inletnozzle 32. The plate 54 extends generally radially to immediatelyadjacent the turbine wheel 34, thereby, dividing the turbine inletnozzle 32 into a primary section (through which air 14 flows when thepoppet member 40 is in the first position illustrated in FIG. 2A) and asecondary section (through which air 14 generally does not pass when thepoppet member 40 is in the first position).

FIG. 2B is an enlarged view of the turbine section 22 with the poppetmember 40 disposed in a second position. In the second position, thefirst cavity 44 is in fluid communication with the ambient air sourceexternal to the air cycle machine 12. As a result of this arrangement,the pressure within the second cavity 48 (the static pressure) exceedsthe second pressure P₂ within the first cavity 44 and the poppet member40 moves decreasing the volume of the first cavity 44 and increasing thevolume of the second cavity 48. The movement of the main body 52 of thepoppet member 40 within the first cavity 44 retracts main body 52 fromat least a portion of the turbine inlet nozzle 32, allowing airflowthrough the secondary section of the turbine inlet nozzle 32, therebyincreasing the size (volume and/or cross sectional area) of the turbineinlet nozzle 32 through which air 14 flows to the turbine wheel 34.Thus, in the second position shown in FIG. 2B virtually the entireairflow passes through the turbine inlet nozzle 32 unrestricted by thepoppet member 40 to the turbine wheel 34.

By varying the pressure of the first cavity 44 in the manner disclosedto selectively move the poppet member 40 within the turbine inlet nozzle32, the efficiency of the environmental control system 10 can beimproved. In particular, selectively moving the poppet member 40 to varythe size of the turbine inlet nozzle 32 when desired allows the powerconsumption of the environmental control system 10 to be reduced, forexample, by operating only a single air conditioning pack to conditionthe cabin rather than operating both air conditioning packs.

Referring to FIGS. 3 and 4, the compressor section 18 may include avariable area diffuser 322 with an actuator 323 (see FIG. 1) to vary theinlet throat 352 (see FIG. 3) to vary a flow rate through the ECS 10.The variable area diffuser 322 includes a backing plate 328 that isisolated from deflection, D. In conventional devices, the backing plate328 would be secured directly to the housing 316 contributing to thediffuser vanes binding. Instead, the inventive diffuser 322 employs amounting plate 330 that supports the backing plate 328. The inner andouter periphery of the backing plate 328 is supported by the mountingplate 330, but is also permitted to move axially independently of themounting plate 330.

A shroud 336 is supported by the housing 316 and may deflect axiallyunder load. Multiple vanes 338 are retained between the backing plate328 and shroud 336 and, typically, a few thousandths of an inch ofclearance is provided between the vane 338 and the backing plate 328 andshroud 336. In the example system shown, there are 323 vanes that aremodulated between full open and 40% of full open.

The vanes 338 include an inlet end 348 and an outlet end 350. The inletend 348 provides an adjustable throat 352, shown in FIG. 2, which isprovided by pivoting the vanes 338. To provide improved containment, thepresent invention includes an aperture 344 arranged between the inletand outlet ends 348 and 350. The aperture is elongated in the directionof the length of the vane 338. Protrusions 346 extend from the backingplate 328 through the aperture 344. In the example shown, theprotrusions 346 are integral with the backing plate 328 and extend toengage the shroud 336. Bolts 340, shown in FIG. 2, extend through theaperture 344 to secure the vane 338 between the shroud 336 and backingplate 328. The additional bolts 340 and protrusions 346 of the presentinvention provide improved containment of the vanes 338 in the event ofa failure.

The mounting plate 330 includes a boss 342 for each vane 338. Each vane338 includes a hole 355 for receiving a pivot pin 354. The pivot pin 354extends through an opening in the shroud to the mounting plate 330 tosecure the vane 338 between the shroud 336 and backing plate 328. An endof the pivot pin 354 is secured into the boss 342. Openings in thebacking plate 328, vane 338 and shroud 336 are in a slip fitrelationship relative to the pivot pin 354 to permit the shroud 336 andbacking plate 328 to deflect axially without binding the vane 338.

The shroud 336 is shown broken along planes J, K and L in FIG. 3 tobetter illustrate the interrelationship of diffuser components. Thevanes 338 include a slot that receives a drive pin 358. The drive pins358 are mounted on a drive ring 356 that is rotated by the actuator 323to rotate the vanes 338 about the pivot pins 354. The drive ring 356includes a bearing 357 supporting the drive ring 356 in the housing 316.The drive pin 358 is received in a slot in the shroud 336 that definesthe positional limits of the vanes 338.

With reference to FIG. 5, the turbine section 22, the compressor section18 and the motor 38 are each mounted on the shaft 20, which acts as acommon rotating shaft, and each is supported on foil air bearings 500(see FIG. 1). The compressor section 18 may have a continuously variablearea diffuser 322 used to provide compressed air utilized for aircraftcabin pressurization and the turbine section 22 may includes a dualnozzle turbine, as described above, with control not limited to turbinepressure ratio in which the poppet member 40 actuates to control turbinenozzle area based upon whether 1 or 2 packs are in operation. Expansionthrough the turbine section 22 may be utilized for supply of cooling airto aircraft cabin C and to generate shaft power to assist the motor 38in driving the compressor section 18.

As shown in FIG. 5, the motor 38 may include an integrally cooled motorthat is disposed in communication with a RAM heat exchanger 501 wherebya pressure differential across the RAM heat exchanger 501 is used togenerate cooling flow. A cooling flow may be tapped from the compressorinlet 24 upstream of the RAM heat exchanger 501 and exited to the RAMducting downstream of the RAM heat exchanger 501. Also, bearing coolingsupply air may be tapped from the compressor outlet 28 and/or aftercooling through the RAM heat exchanger 501.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. An air cycle machine, comprising: a compressor section having avariable area diffuser; a turbine section having an inlet nozzle with avariable size; a motor to drive the compressor; and a common rotatingshaft on which the compressor section, the turbine section and the motorare mounted, the turbine section driving rotation of the shaft to drivethe compressor section with the motor.
 2. The air cycle machineaccording to claim 1, wherein the compressor section, the turbinesection and the motor are each supported on air bearings.
 3. The aircycle machine according to claim 1, wherein the variable size of theinlet nozzle is set according to operation of a predefined number ofpacks.
 4. The air cycle machine according to claim 1, wherein the motorcomprises an integrally cooled motor.
 5. The air cycle machine accordingto claim 4, further comprising a heat exchanger coupled to the motor. 6.The air cycle machine according to claim 5, wherein a first cooling flowis tapped from an inlet of the compressor section and exited downstreamform the heat exchanger.
 7. The air cycle machine according to claim 5,wherein a second cooling flow is tapped from an outlet of the compressorsection for air bearing cooling.
 8. An air cycle machine, comprising: acompressor section having a variable area diffuser to compress inletair; a turbine section having an inlet nozzle with a variable size toreceive the compressed air from the compressor section and to expand theair for use in an aircraft cabin; a motor to drive the compressor; and acommon rotating shaft on which the compressor section, the turbinesection and the motor are operably mounted, the turbine section drivingrotation of the shaft to provide additional drive power to thecompressor section along with that of the motor.
 9. The air cyclemachine according to claim 8, wherein the compressor section, theturbine section and the motor are each supported on air bearings. 10.The air cycle machine according to claim 8, wherein the variable size ofthe inlet nozzle is set according to operation of a predefined number ofpacks.
 11. The air cycle machine according to claim 8, wherein the motorcomprises an integrally cooled motor.
 12. The air cycle machineaccording to claim 11, further comprising a heat exchanger coupled tothe motor.
 13. The air cycle machine according to claim 12, wherein afirst cooling flow is tapped from an inlet of the compressor section andexited downstream form the heat exchanger.
 14. The air cycle machineaccording to claim 12, wherein a second cooling flow is tapped from anoutlet of the compressor section for air bearing cooling.
 15. An aircycle machine for use in a RAM engine in an aircraft, comprising: acompressor section having a variable area diffuser to compress RAM inletair; a turbine section having an inlet nozzle with a variable size toreceive the compressed air from the compressor section and to expand theair for use in a cabin of the aircraft; a motor to drive the compressor;and a common rotating shaft on which the compressor section, the turbinesection and the motor are operably mounted, the turbine section drivingrotation of the shaft to provide additional drive power to thecompressor section along with that of the motor.
 16. The air cyclemachine according to claim 15, wherein the compressor section, theturbine section and the motor are each supported on air bearings. 17.The air cycle machine according to claim 15, wherein the variable sizeof the inlet nozzle is set according to operation of a predefined numberof packs.
 18. The air cycle machine according to claim 15, wherein themotor comprises an integrally cooled motor.
 19. The air cycle machineaccording to claim 18, further comprising a heat exchanger coupled tothe motor.
 20. The air cycle machine according to claim 19, wherein afirst cooling flow is tapped from an inlet of the compressor section andexited downstream form the heat exchanger and a second cooling flow istapped from an outlet of the compressor section for air bearing cooling.